The Supreme Witch, known more colloquially as The Supreme, is a worldwide status recognized among the witches descended from the Salem Witch Trials. While most witches possess only a handful of inherent supernatural gifts, the Supreme is said to embody multiple, if not all. To be identified as the Supreme, the witch in question must have mastery over 7 distinct abilities, known as 'The Seven Wonders', which include the following: Telekinesis, Divination, Transmutation, Pyrokinesis, Concilium, Descensum and Vitalum Vitalis. Historically, there is said to be only one Supreme per generation (approximately 30-50 years), though this may not always be the case; despite Cordelia Foxx having claimed the title, Zoe Benson may prove to be a viable candidate for Supremacy in the future (having displayed all the Seven Wonders in some form throughout the season). Part of being a Supreme means no ailments or diseases; upon first ascending to the title, Cordelia's eyes were fully restored, curing her of her blindness, and Fiona stated that she made the air around her vibrate with sheer power. As time passes, however, the mantle of Supremacy must pass on to a successor, during which the new Supreme flowers while the life force of the former regnant gradually fades, their immune system facing rapid decline in the form of multiple organ failures, disease, diabetes, and cancer until their inevitable death.
The Supreme role comes with the responsibility of the entire coven as the leader of its new generation. "Guided by ancient tradition, witches survived only if united under a strong, singular authority".
One of the most important tasks of the Supreme is to identify their successor; a task that was neglected by former Supreme Fiona Goode. As a result, multiple witches were tested in the Trial of the Seven Wonders, during which one witch died performing descensum.
In cases where a new Supreme must rise before the natural death of the incumbent, a ritual known as "The Sacred Taking" is employed - a stylized suicide of the Supreme blessed by the other members of the coven. It was developed when the ailing Prudence Mather, the Supreme of the 16th century, was not able to make the journey to relocate the coven to New Orleans during the Salem Witch Trials; with her death, she allowed her potential successor to ascend to Supremacy. Fiona inherited her powers earlier than most Supremes (having been around late teens to early twenties at the time) because she killed her generation's Supreme and self-ascended. Fiona lived for a short while after Cordelia's rise to Supremacy, but had already become very weak and sickly, dying in her daughter's arms within moments of witnessing her new status.
The reigning supreme is Cordelia Foxx, who took over from previous supreme Fiona Goode, who was also her mother. Fiona's immediate predecessor was a woman named Anna Leigh Leighton, who ran the school when Fiona was a younger woman, presumably around her late teens. One evening, Fiona questioned her about becoming the next Supreme and how she knew. Anna Leigh informed her of the official test conducted by the Witch Council, but told her not to get her hopes up, informing her that while a witch may possess multiple powers, only a mastery of the Seven Wonders allows for a true demonstration of entitlement to the Supremacy. When Fiona demands to be put to the test, Anna Leigh refuses, stating she was still far too young. The two engage in a heated debate of Anna Leigh's deterioration, both in power and physical health. After Anna Leigh asserts that she would never allow Fiona to take her place for the good of the coven, Fiona surprises her by transmutating in front of her and slashing her throat with a letter-opener, thus taking Anna Leigh's place as the Supreme.
Fiona is the only known Supreme to be related to the next Supreme, Cordelia, putting into question if being born to the Supreme means being their successor, or if this is a mere coincidence.